<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .box {
            position: relative;
            margin: 100px auto;
            width: 100px;
            height: 100px;
        }

        .x {
            width: 8px;
            height: 8px;
            margin: auto;
            background-color: skyblue;
            border-radius: 50%;
        }

        .box div[class^="x"] {
            position: absolute;
            top: 50%;
            left: 50%;
            transform: translate(-50%,-50%);
            width: 8px;
            height: 8px;
            border-radius: 50%;
            box-shadow: 0 0 12px skyblue;
            animation: x 1.2s linear infinite;
        }
        .x_2{
            animation-delay: 0.4s !important;
        }
        .x_3{
            animation-delay: 0.8s !important
        }
        @keyframes x{
            0%{}
            70%{
                width: 20px;
                height: 20px;
                opacity: 1;
            }
            100%{
                width: 40px;
                height: 40px;
                opacity: 0;
            }
        }
    </style>
</head>

<body>
    <div class="box">
        <div class="x"></div>
        <div class="x-1"></div>
        <div class="x_2"></div>
        <div class="x_3"></div>
    </div>
</body>

</html>